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Dynamic mechanical properties and microstructures of pure iron and Fe-30Mn-3Si-4Al TWIP (TWinning Induced Plasticity) steel were conducted by SHPB (Split-Hopkinson Pressure Bar), OM (Optical Microscopy) and TEM (Transmission Electron Microscope), at the strain rate ranging from 102 to 105 s-1 and at room temperature. The effect of high strain rate on the mechanical responses of pure iron and Fe-30Mn-3Si-4Al TWIP steel belonging to BCC (Body Centered Cubic) and FCC (Face Centered Cubic) structures respectively was evaluated. The comparison of deformation mechanism was analyzed between them and it concluded that dislocation gliding is a major deformation mechanism in pure iron with BCC structure and deformation twinning plays a significant role in Fe-30Mn-3Si-4Al TWIP steel with FCC structure.

Abstract: Superplastic forming provides a good way for Ti alloys which are usually difficult to
be deformed. Ti75 alloy with a nominal composition of Ti-3Al-2Mo-2Zr is a newly developed corrosion resistant alloy, with a middle strength and high toughness. In the present paper, superplastic behavior of the alloy was investigated, the microstructural evolution in superplastic deformation was observed and the superplastic deformation mechanisms were analyzed. The results showed that the strain rate sensitivity, m, of the Ti75 alloy was larger than 0.3 and the strain was over 2.0 without surface cracking at 800°C and 5×10-4s-1 in compressive testing.
During the first stage of superplastic deformation, a phase grains became equiaxed, fine and homogeneous due to the recrystallization in a phase and diffusion in b phase. Newly formed equiaxed a grains then could slide and rotate, exhibiting superplastic features. The stress concentration caused by grain sliding of a grains could be released by slip and diffusion in b phase between the a phase grains, which acted as accommodation mechanisms.

Abstract: The hot deformation behaviour of two high-Mn (23-24 wt-%) TWIP steels containing 6
and 8 wt-% Al with the fully austenitic and duplex microstructures, respectively, has been
investigated at temperatures of 900-1100°C. In addition, tensile properties were determined over the
temperature range from -80 to 100°C. It was observed that in spite of the lower Al content, the
austenitic steel possessed the hot deformation resistance about twice as high as that of the duplex
steel. Whereas the flow stress curves of the austenitic steel exhibited work hardening followed by
slight softening due to dynamic recrystallisation, the duplex steel showed the absence of work
hardening and discontinuous yielding under similar conditions. Tensile tests at low temperatures
revealed that the austenitic grade had a lower yield strength than that of the duplex grade, but much
better ductility, the elongation increasing with decreasing temperature, contrary to that for the
duplex steel. This can be attributed to the intense mechanical twinning in the austenitic steel, while
in the duplex steel, twinning occurred in the ferrite only and the austenite showed dislocation glide.

Abstract: The 3003 Al alloy was deformed by isothermal compression in the range of deformation temperature 300-500 °C at strain rate 0.0l-10.0 s-1 with Gleeble-1500 thermal simulator. Processing maps at a strain of 0.6 for hot working were developed on a dynamic materials model. The maps exhibit a flow instability domain at about 300 °C-380 °C and 1.0-10.0 s-1. DRX occurs extensively in the temperature range of 450-500 °C and at the strain rate of 10.0 s-1. The optimum parameters of hot working for 3003 Al alloy at the strain of 0.6 are confined at 500 °C and 10.0 s-1 with the highest efficiency (37%).

Abstract: Uni-axial tensile plastic deformation behavior of rolled magnesium alloy AZ31B under the temperature range from room temperature(RT) to 250°C with strain rates between 10-3 and 10-1s-1 has been systematically investigated. Microstructure evolution and texture were determined using optical microscopy (OM) and electron back-scattered diffraction (EBSD) techniques, respectively. Our results indicated that the strength and elongation-to-fracture were more sensitive to strain rates at elevated temperature rather than that at room temperature; dynamic recrystallization (DRX) and relaxation of stress at elevated temperature resulted in dramatic change of mechanical properties. Compared with strain rate, the temperature played a more important role in ductility of AZ31B Mg alloy sheet.

Abstract: The researches of non-oriented silicon steel are mainly focused on the effect of main processing parameters on the microstructure and magnetic properties, but there have been few studied about its flow stress until now. In this paper, the non-oriented silicon steel 50A1300 of hot forming is studied by thermal-mechanical simulation method. The hot deformation behavior of the steel is explored and the flow stress model of the steel is established based on the creep mechanism. The model has good accuracy and is feasible.